In conventional video cameras (such as 8 mm camcorders), which display an image on a television screen, the camera must be held in the normal horizontal (or "landscape") orientation to obtain a properly oriented image. If the camera is rotated to a vertical (or "portrait") orientation, the displayed television image will likewise be rotated, unless the display screen or viewer are rotated, which is impractical in most television applications. This situation is even more of a problem in practice because there are actually two "portrait" orientations, one for clockwise rotation and the other for counterclockwise rotation. The result is shown in FIG. 1, where for the two "portrait" orientations, the sky appears at the left or right of the screen, rather than at the top. In conventional film-based photography, the film camera may be rotated to any orientation. When vertical "portrait" camera orientations are used to take pictures, the resulting prints are simply rotated when viewed or, alternatively, slides are simply rotated in the viewing projector.
Recent electronic still cameras, such as the Kodak DC 40 camera (sold by Eastman Kodak Co.), allow the user to take still images and display them on a computer screen. Like film cameras, these electronic cameras can be easily rotated so that the image can be composed in either the horizontal "landscape" orientation, or either of the two vertical "portrait" orientations. However, the images initially displayed on the computer screen always assume that the camera was held in the horizontal position. As a result, any pictures taken with the camera in the "portrait" orientations will be rotated so that the sky (upper part of the picture) is at the left or right, rather than at the top. Some computer image processing software, such as Adobe Photoshop.TM. (sold by Adobe Corp.), allows images stored in a computer to be rotated to their proper orientation. However, this is a "manual", time-consuming step, which requires the user to select each and every "portrait" orientation image and perform the proper clockwise or counterclockwise rotation.
Automatic reorientation in a special "album" application is shown in U.S. Pat. No. 5,274,418, as follows. A still video camera captures a plurality of pictures with control information for assembling the pictures into album-like pages. The camera includes an orientation detector that marks the output medium as to orientation. A separate player reads the orientation data and adjusts the images as necessary for proper placement on an album-like page display. This imaging system requires special application programs in the player, which means the orientation correction is dependent upon use with that specific player. As a result, the reorientation is "automatic" only if used with the special application programs in the special player.
Another type of picture processing corrects for unwanted tilting of the camera. As shown in U.S. Pat. No. 5,227,889, a video camera detects, and corrects for, the amount of slant of the entire camera in the vertical direction, due to inclination of the video camera while, e.g., walking. The slant is corrected by controlling the addressing of two field memories, depending on the slant information, thereby delivering an output signal that is corrected for slant of the output moving picture signals in real time. As a result, unwanted camera orientations are corrected in the output signal. While correcting for accidental slant of a motion video camera may make good sense, a still camera is frequently maneuvered so as to purposefully take a slanted picture, e.g., to include all desired picture detail in the still picture. A continuous slant correction would defeat this capability. The problem, in other words, is not with the handling of unwanted situations such as picture slant, but with the handling of desired situations, such as "portrait" orientations, and the provision of appropriate corrections for those situations.